U.S. patent number 8,809,455 [Application Number 12/548,797] was granted by the patent office on 2014-08-19 for elastomeric compositions and their use in articles.
This patent grant is currently assigned to ExxonMobil Chemical Patents Inc.. The grantee listed for this patent is Anthony Jay Dias, Maria D. Ellul, Rodney May. Invention is credited to Anthony Jay Dias, Maria D. Ellul, Rodney May.
United States Patent |
8,809,455 |
Ellul , et al. |
August 19, 2014 |
Elastomeric compositions and their use in articles
Abstract
A dynamically vulcanized alloy contains at least one
isobutylene-containing elastomer and at least one thermoplastic
resin, wherein the elastomer is present as a dispersed phase of
small vulcanized or partially vulcanized particles in a continuous
phase of the thermoplastic resin. The dynamically vulcanized alloy
also contains an anhydride functionalized oligomer. The alloy
maintains a high Shore A hardness value while obtaining improved
flowability for processing.
Inventors: |
Ellul; Maria D. (Silver Lake,
OH), Dias; Anthony Jay (Houston, TX), May; Rodney
(Wadsworth, OH) |
Applicant: |
Name |
City |
State |
Country |
Type |
Ellul; Maria D.
Dias; Anthony Jay
May; Rodney |
Silver Lake
Houston
Wadsworth |
OH
TX
OH |
US
US
US |
|
|
Assignee: |
ExxonMobil Chemical Patents
Inc. (Houston, TX)
|
Family
ID: |
43037796 |
Appl.
No.: |
12/548,797 |
Filed: |
August 27, 2009 |
Prior Publication Data
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|
|
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Document
Identifier |
Publication Date |
|
US 20110054093 A1 |
Mar 3, 2011 |
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Current U.S.
Class: |
525/58; 525/71;
525/66; 525/179; 525/68; 525/187; 525/67; 525/64; 525/189; 525/60;
525/133; 525/166; 525/65 |
Current CPC
Class: |
C08L
23/22 (20130101); C08K 3/34 (20130101); C08K
5/0016 (20130101); C08L 23/02 (20130101); C08L
77/00 (20130101); C08L 23/283 (20130101); B60C
1/00 (20130101); C08L 23/0869 (20130101); C08L
23/02 (20130101); C08L 2666/02 (20130101); C08L
23/22 (20130101); C08K 3/34 (20130101); C08K
5/0016 (20130101); C08L 23/0869 (20130101); C08L
77/00 (20130101); C08L 2205/08 (20130101); C08L
2666/02 (20130101); C08L 23/283 (20130101); C08L
2666/02 (20130101); C08L 77/00 (20130101); C08L
2666/02 (20130101); C08L 79/08 (20130101); C08L
2666/02 (20130101); C08L 2205/08 (20130101) |
Current International
Class: |
C08L
29/04 (20060101); C08L 55/02 (20060101); C08L
81/06 (20060101); C08L 81/04 (20060101); C08L
79/00 (20060101); C08L 77/00 (20060101); C08L
67/00 (20060101) |
Field of
Search: |
;525/58,60,64,65,66,67,68,71,133,166,179,187,189,191 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 722 850 |
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May 1999 |
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EP |
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0 969 039 |
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Jan 2000 |
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EP |
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1 995 275 |
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Nov 2008 |
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EP |
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WO2007/070063 |
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Jun 2007 |
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WO |
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WO 2007/100157 |
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Sep 2007 |
|
WO |
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WO 2009/048472 |
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Apr 2009 |
|
WO |
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WO2009/048472 |
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Apr 2009 |
|
WO |
|
Other References
Jiri George Drobny, Handbook of Thermoplastic Elastomers, William
Andrew Inc., New York, p. 23 and pp. 179-190, 2007. cited by
applicant .
Brendan Rodgers ed., Rubber Compounding Chemistry and Applications,
CRC Press LLC, p. 365 and pp. 394-399, 2004. cited by
applicant.
|
Primary Examiner: Woodward; Ana
Attorney, Agent or Firm: Krawczyk; Nancy T.
Claims
What is claimed is:
1. A dynamically vulcanized alloy comprising the four following
components: a) at least one isobutylene-containing elastomer; b) at
least one polar thermoplastic resin, c) an anhydride functionalized
oligomer, wherein the oligomer, prior to functionalization, has a
molecular weight in the range of 750 to 1250, and d) a plasticizer,
the plasticizer comprising a component selected from the group
consisting of tertiary amines, secondary diamines, and
sulfonamides, wherein the anhydride functionalized oligomer and the
plasticizer are present in the alloy in a ratio ranging from 0.3 to
1.5, and wherein the anhydride functionality of the oligomer is
grafted to the polar thermoplastic resin and the elastomer is
present as a dispersed phase of small vulcanized or partially
vulcanized particles in a continuous phase of the thermoplastic
resin.
2. The alloy of claim 1, wherein the oligomer is selected from the
group consisting of an alkyl, an aryl, and an alkenyl oligomer.
3. The alloy of claim 1, wherein the anhydride functionality is
either a succinic anhydride or a maleic anhydride.
4. The alloy of claim 1, wherein the anhydride functionalized
oligomer is a poly-n-alkyl succinic anhydride or a poly-iso-alkyl
succinic anhydride.
5. The alloy of claim 1, wherein the functionalized oligomer is
selected from the group consisting of poly-isobutylene succinic
anhydride, polyisobutene succinic anhydride, polybutene succinic
anhydride, polyisopentene succinic anhydride, polypentene succinic
anhydride, polyoctenyl succinic anhydride, polyisooctenyl succinic
anhydride, poly-hexenyl succinic anhydride, and poly-dodecenyl
succinic anhydride.
6. The alloy of claim 1, wherein the alloy comprises 2 to 35 phr of
the anhydride functionalized oligomer, based on the amount of the
isobutylene-containing elastomer in the alloy.
7. The alloy of claim 1, wherein the alloy is substantially free of
any acrylates.
8. The alloy of claim 1, wherein said elastomer is a halogenated
butyl rubber.
9. The alloy of claim 1, wherein said elastomer is a copolymer of
isobutylene and an alkylstyrene.
10. The alloy of claim 1, wherein said elastomer is a copolymer of
isobutylene and paramethylstyrene, and is optionally
halogenated.
11. The alloy of claim 1, wherein the thermoplastic resin is
selected from the group consisting of polyamides, polyimides,
polycarbonates, polyesters, polysulfones, polylactones,
acrylonitrile-butadiene-styrene resins, polyphenylene sulfide,
styrene-acrylonitrile resins, styrene maleic anhydride resins,
aromatic polyketones, ethylene vinyl acetates, ethylene vinyl
alcohols, and mixtures thereof.
12. The alloy of claim 1, wherein the elastomer is present in the
alloy in an amount in the range of 2 to 90 weight percent.
13. The alloy of claim 1, wherein the total amount of the anhydride
functionalized oligomer and the plasticizer is present in an amount
of 5 phr to 35 phr based on the amount of the
isobutylene-containing elastomer in the alloy.
14. The alloy of claim 1, wherein the oligomer has an anhydride
level of 5 to 25 wt %.
15. A dynamically vulcanized alloy comprising the following
components: a) at least one isobutylene-containing elastomer; b) at
least one polar thermoplastic resin, c) an anhydride functionalized
oligomer wherein the oligomer has a molecular weight, prior to
functionalization, in the range of 750 to 1250 and the anhydride
functionality is grafted to the polar thermoplastic resin, and d) a
plasticizer, the plasticizer comprising a component selected from
the group consisting of tertiary amines, secondary diamines, and
sulfonamides, wherein the total amount of anhydride functionalized
oligomer and the plasticizer is present in an amount of 5 phr to 35
phr based on the amount of the isobutylene-containing elastomer in
the alloy, and the anhydride functionalized oligomer and the
plasticizer are present in a ratio ranging from 0.15 to 3.0, and
wherein the elastomer is present as a dispersed phase of small
vulcanized or partially vulcanized particles in a continuous phase
of the thermoplastic resin.
16. The alloy of claim 15 wherein the elastomer is present in the
alloy in an amount in the range of 2 to 90 weight percent.
17. The alloy of claim 15 wherein the anhydride functionality is
either a succinic anhydride or a maleic anhydride and the oligomer
is selected from the group consisting of an alkyl, an aryl, and an
alkenyl oligomer.
Description
FIELD OF THE INVENTION
The present invention relates to thermoplastic elastomeric
compositions. More particularly, the present invention is directed
to a thermoplastic elastomeric composition comprising compounds
that act as both an extender and reactive plasticizer for the
thermoplastic in the composition.
BACKGROUND
The present invention is related to thermoplastic elastomeric
compositions particularly useful for tire and other industrial
rubber applications, reinforced or otherwise, that require
impermeability characteristics.
EP 0 722 850 B1 discloses a low-permeability thermoplastic
elastomeric composition that is excellent as an innerliner in
pneumatic tires. This composition comprises a low permeability
thermoplastic in which is dispersed a low permeability rubber. EP 0
969 039 A1 discloses a similar composition and teaches that the
small particle size rubber dispersed in the thermoplastic was
important to achieve acceptable durability of the resulting
composition.
There are also examples of the use of a thermoplastic elastomer
composed of a rubber and a thermoplastic for use as an innerliner
in a tire. But, in general, a flexible material of the type
disclosed therein has low heat resistance. When the thermoplastic
material in the composition has a melting point less than the tire
vulcanization temperature, when the tire curing bladder is released
at the end of the curing cycle, the inside surface of the tire may
have defects due to the thermoplastic material of the composition
sticking to rubber of the curing bladder.
Controlling the viscosity difference between the two different
materials in the composition is also considered important, as the
viscosity difference affects the dispersed rubber particle size.
However, when seeking to maintain a ratio of melt viscosities of
the rubber/plastic at 1.0 (one), the rubber may dominate the matrix
and the composition no longer exhibits a desired thermoplasticity,
see EP 0 969 039 A1.
SUMMARY OF THE INVENTION
The present invention is directed to a thermoplastic elastomeric
composition having improved characteristics over previously known
similar compositions.
The present invention is directed to a dynamically vulcanized alloy
containing at least one isobutylene-containing elastomer and at
least one thermoplastic resin, wherein the elastomer is present as
a dispersed phase of small vulcanized or partially vulcanized
particles in a continuous phase of the thermoplastic resin. The
dynamically vulcanized alloy also contains therein an anhydride
functionalized oligomer.
In another aspect of the disclosed invention, the oligomer of the
anhydride functionalized oligomer, prior to functionalization, has
a molecular weight in the range of 500 to 5000. In another aspect
of the invention, the oligomer has a molecular weight in the range
of 750 to 2500.
In one aspect of the disclosed invention, the oligomer is an alkyl,
an aryl, or an alkenyl oligomer and the anhydride is either a
maleic or a succinic anhydride. In another aspect of the invention,
the succinic anhydride functionalized polymer is a poly-n-alkyl
succinic anhydride or a poly-iso-alkyl succinic anhydride.
In another aspect of the invention, the functionalized oligomer is
selected from the group consisting of poly-isobutylene succinic
anhydride, polyisobutene succinic anhydride, polybutene succinic
anhydride, polyisopentene succinic anhydride, polypentene succinic
anhydride, polyoctenyl succinic anhydride, polyisooctenyl succinic
anhydride, poly-hexenyl succinic anhydride, poly-dodecenyl succinic
anhydride.
In another aspect of the invention, the alloy contains 2 to 35 phr
of the succinic anhydride functionalized polymer, based on the
amount of the isobutylene-containing elastomer in the alloy.
In another aspect of the invention, the alloy further includes a
plasticizer. The plasticizer may be a polyamide, tertiary amine,
secondary diamine, ester, or sulfonamide. Preferably, the ratio of
succinic anhydride functionalized oligomer to plasticizer is in the
range of 0.15 to 3.0.
In another aspect of the invention, the alloy is substantially free
of any acrylates and preferably, the alloy is devoid of any
acrylates.
In another aspect of the invention, the isobutylene containing
elastomer is a halogenated butyl rubber. In another aspect of the
invention, the isobutylene containing elastomer is a random
copolymer of isobutylene and an alkylstyrene. Preferably, when the
elastomer is the random copolymer of isobutylene and an
alkylstyrene, the alkylstyrene is paramethylstyrene. In any
embodiment, the elastomer may be halogenated with bromine or
chlorine.
In another aspect of the invention, the isobutylene containing
elastomer is present in the alloy in an amount in the range of 2 to
90 weight percent.
In another aspect of the invention, the thermoplastic resin is
selected from the group consisting of polyamides, polyimides,
polycarbonates, polyesters, polysulfones, polylactones,
polyacetals, acrylonitrile-butadiene-styrene resins,
polyphenyleneoxide, polyphenylene sulfide, polystyrene,
styrene-acrylonitrile resins, styrene maleic anhydride resins,
aromatic polyketones, ethylene vinyl acetate, ethylene vinyl
alcohol, and mixtures thereof.
In another aspect of the invention, the alloy has a Shore A
hardness of at least 70.
DETAILED DESCRIPTION OF THE INVENTION
Various specific embodiments, versions, and examples of the
invention will now be described, including preferred embodiments
and definitions that are adopted herein for purposes of
understanding the claimed invention. While the illustrative
embodiments have been described with particularity, it will be
understood that various other modifications will be apparent to and
can be readily made by those skilled in the art without departing
from the spirit and scope of the invention. For determining
infringement, the scope of the "invention" will refer to any one or
more of the appended claims, including their equivalents and
elements or limitations that are equivalent to those that are
recited.
DEFINITIONS
Definitions applicable to the presently described invention are as
described below.
Polymer may be used to refer to homopolymers, copolymers,
interpolymers, terpolymers, etc. Likewise, a copolymer may refer to
a polymer comprising at least two monomers, optionally with other
monomers. When a polymer is referred to as comprising a monomer,
the monomer is present in the polymer in the polymerized form of
the monomer or in the polymerized form of a derivative from the
monomer (i.e. a monomeric unit). However, for ease of reference the
phrase comprising the (respective) monomer or the like is used as
shorthand. Likewise, when catalyst components are described as
comprising neutral stable forms of the components, it is well
understood by one skilled in the art, that the ionic form of the
component is the form that reacts with the monomers to produce
polymers.
Rubber refers to any polymer or composition of polymers consistent
with the ASTM D1566 definition: "a material that is capable of
recovering from large deformations, and can be, or already is,
modified to a state in which it is essentially insoluble, if
vulcanized, (but can swell) in a solvent . . . ". Rubbers are often
also referred to as elastomers; the term elastomer may be used
herein interchangeably with the term rubber.
The term "phr" is parts per hundred rubber or "parts", and is a
measure common in the art wherein components of a composition are
measured relative to a total of all of the elastomer components.
The total phr or parts for all rubber components, whether one, two,
three, or more different rubber components is present in a given
recipe is normally defined as 100 phr. All other non-rubber
components are ratioed against the 100 parts of rubber and are
expressed in phr. This way one can easily compare, for example, the
levels of curatives or filler loadings, etc., between different
compositions based on the same relative proportion of rubber
without the need to recalculate percentages for every component
after adjusting levels of only one, or more, component(s).
Isoolefin refers to any olefin monomer having at least one carbon
having two substitutions on that carbon. Multiolefin refers to any
monomer having two or more double bonds. In a preferred embodiment,
the multiolefin is any monomer comprising two conjugated double
bonds such as a conjugated diene like isoprene.
Isobutylene based elastomer or polymer refers to elastomers or
polymers comprising at least 70 mol % repeat units from
isobutylene.
Elastomer
Useful elastomeric compositions for this invention comprise a
mixture of monomers, the mixture having at least (1) a C.sub.4 to
C.sub.7 isoolefin monomer component with (2) a multiolefin, monomer
component. The isoolefin is present in a range from 70 to 99.5 wt %
by weight of the total monomers in one embodiment, and 85 to 99.5
wt % in another embodiment. The multiolefin component is present in
amounts in the range of from 30 to about 0.5 wt % in one
embodiment, and from 15 to 0.5 wt % in another embodiment. In yet
another embodiment, from 8 to 0.5 wt % of the monomer mixture is
multiolefin.
The isoolefin is a C.sub.4 to C.sub.7 compound, non-limiting
examples of which are compounds such as isobutylene, isobutene,
2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene, 1-butene,
2-butene, methyl vinyl ether, indene, vinyltrimethylsilane, hexene,
and 4-methyl-1-pentene. The multiolefin is a C.sub.4 to C.sub.14
multiolefin such as isoprene, butadiene,
2,3-dimethyl-1,3-butadiene, myrcene, 6,6-dimethyl-fulvene,
hexadiene, cyclopentadiene, and piperylene. Other polymerizable
monomers such as styrene and dichlorostyrene are also suitable for
homopolymerization or copolymerization in butyl rubbers.
Preferred elastomers useful in the practice of this invention
include isobutylene-based copolymers. As stated above, an
isobutylene based elastomer or a polymer refers to an elastomer or
a polymer comprising at least 70 mol % repeat units from
isobutylene and at least one other polymerizable unit. The
isobutylene-based copolymer may or may not be halogenated.
In one embodiment of the invention, the elastomer is a butyl-type
rubber or branched butyl-type rubber, especially halogenated
versions of these elastomers. Useful elastomers are unsaturated
butyl rubbers such copolymers of olefins or isoolefins and
multiolefins. Non-limiting examples of unsaturated elastomers
useful in the method and composition of the present invention are
poly(isobutylene-co-isoprene), polyisoprene, polybutadiene,
polyisobutylene, poly(styrene-co-butadiene), natural rubber,
star-branched butyl rubber, and mixtures thereof. Useful elastomers
in the present invention can be made by any suitable means known in
the art, and the invention is not herein limited by the method of
producing the elastomer.
One embodiment of the butyl rubber polymer of the invention is
obtained by reacting 95 to 99.5 wt % of isobutylene with 0.5 to 8
wt % isoprene, or from 0.5 wt % to 5.0 wt % isoprene in yet another
embodiment.
Elastomeric compositions of the present invention may also comprise
at least one random copolymer comprising a C.sub.4 to C.sub.7
isomonoolefins, such as isobutylene, and an alkylstyrene comonomer,
such as para-methylstyrene, containing at least 80%, more
alternatively at least 90% by weight of the para-isomer and
optionally include functionalized interpolymers wherein at least
one or more of the alkyl substituents groups present in the styrene
monomer units contain benzylic halogen or some other functional
group. In another embodiment, the polymer may be a random
elastomeric copolymer of a C.sub.4 to C.sub.6 .alpha.-olefin and an
alkylstyrene comonomer, such as para-methylstyrene containing at
least 80%, alternatively at least 90% by weight of the para-isomer
and optionally include functionalized interpolymers wherein at
least one or more of the alkyl substituents groups present in the
styrene monomer units contain benzylic halogen or some other
functional group. Exemplary materials may be characterized as
polymers containing the following monomer units randomly spaced
along the polymer chain:
##STR00001## wherein R and R.sup.1 are independently hydrogen,
lower alkyl, such as a C.sub.1 to C.sub.7 alkyl and primary or
secondary alkyl halides and X is a functional group such as
halogen. In an embodiment, R and R.sup.1 are each hydrogen. Up to
60 mol % of the para-substituted styrene present in the random
polymer structure may be the functionalized structure (2) above in
one embodiment, and in another embodiment from 0.1 to 5 mol %. In
yet another embodiment, the amount of functionalized structure (2)
is from 0.2 to 3 mol %.
The functional group X may be halogen or some other functional
group which may be incorporated by nucleophilic substitution of
benzylic halogen with other groups such as carboxylic acids;
carboxy salts; carboxy esters, amides and imides; hydroxy;
alkoxide; phenoxide; thiolate; thioether; xanthate; cyanide;
cyanate; amino and mixtures thereof. These functionalized
isomonoolefin copolymers, their method of preparation, methods of
functionalization, and cure are more particularly disclosed in U.S.
Pat. No. 5,162,445.
In an embodiment, the elastomer comprises random polymers of
isobutylene and 0.5 to 20 mol % para-methylstyrene wherein up to 60
mol % of the methyl substituent groups present on the benzyl ring
is functionalized with a halogen such a bromine or chlorine
(para-(bromomethylstyrene)), an acid, or an ester.
In another embodiment, the functionality is selected such that it
can react or form polar bonds with functional groups present in the
matrix polymer, for example, acid, amino or hydroxyl functional
groups, when the polymer components are mixed at high
temperatures.
In one embodiment, brominated poly(isobutylene-co-p-methylstyrene)
"BIMSM" polymers generally contain from 0.1 to 5 mol % of
bromomethylstyrene groups relative to the total amount of monomer
derived units in the copolymer. In another embodiment, the amount
of bromomethyl groups is from 0.2 to 3.0 mol %, and from 0.3 to 2.8
mol % in yet another embodiment, and from 0.4 to 2.5 mol % in yet
another embodiment, and from 0.3 to 2.0 mol % in yet another
embodiment, wherein a desirable range may be any combination of any
upper limit with any lower limit. Expressed another way, exemplary
copolymers contain from 0.2 to 10 wt % of bromine, based on the
weight of the polymer, from 0.4 to 6 wt % bromine in another
embodiment, and from 0.6 to 5.6 wt % in another embodiment, are
substantially free of ring halogen or halogen in the polymer
backbone chain. In one embodiment, the random polymer is a
copolymer of C.sub.4 to C.sub.7 isoolefin derived units (or
isomonoolefin), para-methylstyrene derived units and
para-(halomethylstyrene) derived units, wherein the
para-(halomethylstyrene) units are present in the polymer from 0.4
to 3.0 mol % based on the total number of para-methylstyrene, and
wherein the para-methylstyrene derived units are present from 3 to
15 wt % based on the total weight of the polymer in one embodiment,
and from 4 to 10 wt % in another embodiment. In another embodiment,
the para-(halomethylstyrene) is para-(bromomethylstyrene).
Thermoplastic Resin
For purposes of the present invention, a thermoplastic
(alternatively referred to as thermoplastic resin) is a
thermoplastic polymer, copolymer, or mixture thereof having a
Young's modulus of more than 200 MPa at 23.degree. C. The resin
should have a melting temperature of about 170.degree. C. to about
260.degree. C., preferably less than 260.degree. C., and most
preferably less than about 240.degree. C. By conventional
definition, a thermoplastic is a synthetic resin that softens when
heat is applied and regains its original properties upon
cooling.
Such thermoplastic resins may be used singly or in combination and
generally contain nitrogen, oxygen, halogen, sulfur or other groups
capable of interacting with an aromatic functional groups such as
halogen or acidic groups. Suitable thermoplastic resins include
resins selected from the group consisting or polyamides,
polyimides, polycarbonates, polyesters, polysulfones, polylactones,
polyacetals, acrylonitrile-butadiene-styrene resins (ABS),
polyphenyleneoxide (PPO), polyphenylene sulfide (PPS), polystyrene,
styrene-acrylonitrile resins (SAN), styrene maleic anhydride resins
(SMA), aromatic polyketones (PEEK, PED, and PEKK), ethylene
copolymer resins (EVA or EVOH) and mixtures thereof.
Suitable polyamides (nylons) comprise crystalline or resinous, high
molecular weight solid polymers including copolymers and
terpolymers having recurring amide units within the polymer chain.
Polyamides may be prepared by polymerization of one or more epsilon
lactams such as caprolactam, pyrrolidione, lauryllactam and
aminoundecanoic lactam, or amino acid, or by condensation of
dibasic acids and diamines. Both fiber-forming and molding grade
nylons are suitable. Examples of such polyamides are
polycaprolactam (nylon-6), polylauryllactam (nylon-12),
polyhexamethyleneadipamide (nylon-6,6) polyhexamethyleneazelamide
(nylon-6,9), polyhexamethylenesebacamide (nylon-6,10),
polyhexamethyleneisophthalamide (nylon-6, IP) and the condensation
product of 11-amino-undecanoic acid (nylon-11). Commercially
available polyamides may be advantageously used in the practice of
this invention, with linear crystalline polyamides having a
softening point or melting point between 160 and 260.degree. C.
being preferred.
Suitable polyesters which may be employed include the polymer
reaction products of one or a mixture of aliphatic or aromatic
polycarboxylic acids esters of anhydrides and one or a mixture of
diols. Examples of satisfactory polyesters include
poly(trans-1,4-cyclohexylene C.sub.2-6 alkane dicarboxylates such
as poly(trans-1,4-cyclohexylene succinate) and
poly(trans-1,4-cyclohexylene adipate); poly (cis or
trans-1,4-cyclohexanedimethylene)alkanedicarboxylates such as
poly(cis-1,4-cyclohexanedimethylene)oxlate and
poly-(cis-1,4-cyclohexanedimethylene)succinate, poly(C.sub.2-4
alkylene terephthalates) such as polyethyleneterephthalate and
polytetramethylene-terephthalate, poly(C.sub.2-4 alkylene
isophthalates such as polyethyleneisophthalate and
polytetramethylene-isophthalate and like materials. Preferred
polyesters are derived from aromatic dicarboxylic acids such as
naphthalenic or phthalic acids and C.sub.2 to C.sub.4 diols, such
as polyethylene terephthalate and polybutylene terephthalate.
Preferred polyesters will have a melting point in the range of
160.degree. C. to 260.degree. C.
Poly(phenylene ether) (PPE) resins which may be used in accordance
with this invention are well known, commercially available
materials produced by the oxidative coupling polymerization of
alkyl substituted phenols. They are generally linear, amorphous
polymers having a glass transition temperature in the range of
190.degree. C. to 235.degree. C.
Ethylene copolymer resins useful in the invention include
copolymers of ethylene with unsaturated esters of lower carboxylic
acids as well as the carboxylic acids per se. In particular,
copolymers of ethylene with vinylacetate or alkyl acrylates for
example methyl acrylate and ethyl acrylate can be employed. These
ethylene copolymers typically comprise about 60 to about 99 wt %
ethylene, preferably about 70 to 95 wt % ethylene, more preferably
about 75 to about 90 wt % ethylene. The expression "ethylene
copolymer resin" as used herein means, generally, copolymers of
ethylene with unsaturated esters of lower (C.sub.1-C.sub.4)
monocarboxylic acids and the acids themselves; e.g. acrylic acid,
vinyl esters or alkyl acrylates. It is also meant to include both
"EVA" and "EVOH", which refer to ethylene-vinylacetate copolymers,
and their hydrolyzed counterpart ethylene-vinyl alcohols.
Thermoplastic Elastomeric Composition
At least one of any of the above elastomers and at least one of any
of the above thermoplastics are blended to form a dynamically
vulcanized alloy. The term "dynamic vulcanization" is used herein
to connote a vulcanization process in which the vulcanizable
elastomer is vulcanized in the presence of a thermoplastic under
conditions of high shear and elevated temperature. As a result, the
vulcanizable elastomer is simultaneously crosslinked and preferably
becomes dispersed as fine sub micron size particles of a "micro
gel" within the thermoplastic. The resulting material is often
referred to as a dynamically vulcanized alloy ("DVA").
Dynamic vulcanization is effected by mixing the ingredients at a
temperature which is at or above the curing temperature of the
elastomer, and also above the melt temperature of the thermoplastic
component, in equipment such as roll mills, Banbury.TM. mixers,
continuous mixers, kneaders or mixing extruders, e.g., twin screw
extruders. The unique characteristic of the dynamically cured
compositions is that, notwithstanding the fact that the elastomer
component may be fully cured, the compositions can be processed and
reprocessed by conventional thermoplastic processing techniques
such as extrusion, injection molding, compression molding, etc.
Scrap or flashing can also be salvaged and reprocessed; those
skilled in the art will appreciate that conventional elastomeric
thermoset scrap, comprising only elastomer polymers, cannot readily
be reprocessed due to the cross-linking characteristics of the
vulcanized polymer.
Preferably the thermoplastic may be present in an amount ranging
from about 10 to 98 wt %, preferably from about 20 to 95 wt %, the
elastomer may be present in an amount ranging from about 2 to 90 wt
%, preferably from about 5 to 80 wt %, based on the polymer
blend.
The elastomer may be present in the composition in a range from up
to 90 wt % in one embodiment, from up to 50 wt % in another
embodiment, from up to 40 wt % in another embodiment, and from up
to 30 wt % in yet another embodiment. In yet another embodiment,
the elastomer may be present from at least 2 wt %, and from at
least 5 wt % in another embodiment, and from at least 5 wt % in yet
another embodiment, and from at least 10 wt % in yet another
embodiment. A desirable embodiment may include any combination of
any upper wt % limit and any lower wt % limit.
In preparing the DVA, other materials may be blended with either
the elastomer or the thermoplastic, before the elastomer and the
thermoplastic are combined in the blender, or added to the mixer
during or after the thermoplastic and elastomer have already been
introduced to each other. These other materials may be added to
assist with preparation of the DVA or to provide desired physical
properties to the DVA. Such additional materials include, but are
not limited to, curatives, compatibilizers, extenders, and
plasticizers.
With reference to the elastomers of the disclosed invention,
"vulcanized" or "cured" refers to the chemical reaction that forms
bonds or cross-links between the polymer chains of the elastomer.
Curing of the elastomer is generally accomplished by the
incorporation of the curing agents and/or accelerators, with the
overall mixture of such agents referred to as the cure system or
cure package.
Suitable curing components include sulfur, metal oxides,
organometallic compounds, radical initiators. Common curatives
include ZnO, CaO, MgO, Al2O3, CrO3, FeO, Fe2O3, and NiO. These
metal oxides can be used in conjunction with metal stearate
complexes (e.g., the stearate salts of Zn, Ca, Mg, and Al), or with
stearic acid or other organic acids and either a sulfur compound or
an alkyl or aryl peroxide compound or diazo free radical
initiators. If peroxides are used, peroxide co-agent commonly used
in the art may be employed. The use of peroxide curative may be
avoided if the thermoplastic resin is one such that the presence of
peroxide would cause the thermoplastic resin to cross-link.
As noted, accelerants (also known as accelerators) may be added
with the curative to form a cure package. Suitable curative
accelerators include amines, guanidines, thioureas, thiazoles,
thiurams, sulfenamides, sulfenimides, thiocarbamates, xanthates,
and the like. Numerous accelerators are known in the art and
include, but are not limited to, the following: stearic acid,
diphenyl guanidine (DPG), tetramethylthiuram disulfide (TMTD),
4,4'-dithiodimorpholine (DTDM), tetrabutylthiuram disulfide (TBTD),
2,2'-benzothiazyl disulfide (MBTS),
hexamethylene-1,6-bisthiosulfate disodium salt dihydrate,
2-(morpholinothio)benzothiazole (MBS or MOR), compositions of 90%
MOR and 10% MBTS (MOR90), N-tertiarybutyl-2-benzothiazole
sulfenamide (TBBS), and N-oxydiethylene
thiocarbamyl-N-oxydiethylene sulfonamide (OTOS), zinc 2-ethyl
hexanoate (ZEH), N,N'-diethyl thiourea.
In one embodiment of the invention, at least one curing agent,
preferably zinc oxide, is typically present at about 0.1 to about
15 phr; alternatively at about 0.5 to about 10 phr, or at about 1.0
to 2.0 phr.
In an embodiment of the DVA, due to the goal of the elastomer being
present as discrete particles in a thermoplastic domain, the
addition of the curing components and the temperature profile of
the components are adjusted to ensure the correct morphology is
developed. Thus, if there are multiple mixing stages in the
preparation of the DVA, the curatives may be added during an
earlier stage wherein the elastomer alone is being prepared.
Alternatively, the curatives may be added just before the elastomer
and thermoplastic resin are combined or even after the
thermoplastic has melted and been mixed with the rubber. Although
discrete rubber particle morphology in a continuous thermoplastic
matrix is the preferred morphology, the invention is not limited to
only this morphology and may also include morphologies where both
the elastomer and the thermoplastic are continuous. Sub-inclusions
of the thermoplastic inside the rubber particles may also be
present.
Compatibilizers may be employed due to the difference in solubility
of the thermoplastic resins and elastomers in the DVA. Such
compatilizers are thought to function by modifying, and in
particular reducing, the surface tension between the rubber and
thermoplastic components of the composition. Suitable
compatibilizers include ethylenically unsaturated
nitrile-conjugated diene-based high saturation copolymer rubbers
(HNBR), epoxylated natural rubbers (ENR), acrylate rubber, and
mixtures thereof, as well as copolymers having the same structure
of the thermoplastic resin or the elastomeric polymer, or a
structure of a copolymer having an epoxy group, carbonyl group,
halogen group, amine group, maleated group, oxazoline group, or
hydroxyl group capable of reacting with the thermoplastic resin or
the elastomer.
The amount of compatibilizer is typically about 0.5 to about 10
parts by weight; preferably about 3 to about 8 parts by weight,
based upon 100 parts by weight of the total of the elastomer.
Minimizing the viscosity differential between the elastomer and the
thermoplastic resin components during mixing and/or processing
enhances uniform mixing and fine blend morphology that
significantly enhance good blend mechanical as well as desired
permeability properties. However, as a consequence of the flow
activation and shear thinning characteristic inherent in
elastomeric polymers, reduced viscosity values of the elastomeric
polymers at the elevated temperatures and shear rates encountered
during mixing are much more pronounced than the reductions in
viscosity of the thermoplastic component with which the elastomer
is blended. It is desired to reduce this viscosity difference
between the materials to achieve a DVA with acceptable elastomeric
dispersion sizes.
Components previously used to compatibilize the viscosity between
the elastomer and thermoplastic components include low molecular
weight polyamides, maleic anhydride grafted polymers having a
molecular weight on the order of 10,000 or greater, methacrylate
copolymers, tertiary amines and secondary diamines. Examples
include maleic anhydride-grafted ethylene-ethyl acrylate copolymers
(a solid rubbery material available from Mitsui-DuPont as AR-201
having a melt flow rate of 7 g/10 min measured per JIS K6710) and
n-butyl benzene sulfonamide (BBSA). These compounds may act to
increase the `effective` amount of thermoplastic material in the
elastomeric/thermoplastic compound. The amount of additive is
selected to achieve the desired viscosity comparison without
negatively affecting the characteristics of the DVA. If too much is
present, impermeability may be decreased and the excess may have to
be removed during post-processing. If not enough compatibilizer is
present, the elastomer may not invert phases to become the
dispersed phase in the thermoplastic resin matrix.
In the present invention, the limitations of known compatibilizers
are reduced by, among other things, employing anhydride grated
oligomers as a plasticizer or viscosity modifier for the DVA in
place of conventional compatibilizers or plasticizers. Anhydride
moieties, both maleic and succinic anhydride moities, have an
affinity and compatibility with the thermoplastics employed in the
compositions of this invention. The anhydrides are miscible or
sufficiently compatible with the thermoplastic, and, not wishing to
be bound by any theory, it is believed that the anhydrides may also
act as scavengers for any terminal amines in the thermoplastic,
causing the succinic anhydride to graft to the thermoplastic and
reduce the use of other plasticizers and compatibilizers. As a
result of the grafting reaction, the anhydride functionalized
oligomer is fixed within the DVA, and does not volatize out like
conventional plasticizers/compatibilizers during post DVA
processing operations such as film blowing or tire curing. Thus,
the resulting DVA has a low volatile organic compound emissions.
This is believed to be most applicable when using polar
thermoplastics. Furthermore, it was surprisingly found that the
melting point of a polyamide thermoplastic phase is invariant when
the anhydrides are used, contrary to traditional plasticizers for
polyamide thermoplastics such as n-butyl benzene sulfonamides that
negatively depress the melting point of the thermoplastic.
Both maleic and succinic anhydrides (both aromatic anhydrides) are
useful in the present invention. Preferred anhydrides are
substituted succinic anhydrides, wherein the substitution can be an
alkyl, aryl, or alkenyl. The substituted succinic anhydride may be
prepared by thermal or chloro methods known in the art of reacting
an alkyl, aryl, or olefin with maleic anhydride. The oligomer,
including copolymers of lower olefins, being reacted with the
maleic or succinic anhydride, has a molecular weight in the range
of about 500 to 5000, alternatively 750 to 2500, or alternatively
500 to 1500. The oligomer may also have a molecular weight in the
ranges of 1000 to 5000, 800 to 2500, or 750 to 1250. Specific
examples of substituted succinic anhydrides include
poly-isobutylene succinic anhydride, n-octenyl succinic anhydride,
n-hexenyl succinic anhydride, and dodocenyl succinic anhydride.
The most preferred anhydride functionalized oligomers for this
invention are those derived from polyisobutene and are commonly
known as polyisobutylene succinic anhydride or polyisobutene
succinic anhydride (PIBSA). The PIBSA may be made by cationic
polymerization of isobutene with boron trifluoride as catalyst. In
the course of the polymerization, high concentrations of
.alpha.-olefins are formed during the transfer reaction and as a
result the polymerization product has a high proportion of terminal
double bonds (.alpha.-olefin). They are normally clear to amber
viscous liquids and are specially optimized during the post
polymerization maleitation reaction to have a low bismaleination.
The anhydride level of the PIBSA can vary and a preferred range is
a few percent up to about 30 wt % with a preferred range of 5 to 25
wt % and a more preferred range of 7 to 17 wt % and a most
preferred range of 9 to 15 wt %.
Succinic anhydrides functionalized oligomers are present in the DVA
in amounts ranging from a minimum amount of about 2 phr, 5 phr, or
10 phr to a maximum amount of 15 phr, 20 phr, 25 phr, 30 phr, or 35
phr. The range of succinic anhydride oligomer may range from any of
the above stated minimums to any of the above stated maximums, and
the amount of succinic anhydride functionalized oligomer may fall
within any of the ranges.
The succinic anhydride functionalized oligomer may also replace a
portion of the plasticizers, such as butyl benzene sulfonamide or
other sulfonamides, which are commonly used in a polyamide-based
DVA compound. When the succinic anhydride functionalized oligomer
replaces a portion of the plasticizer, the total amount of
replacement is not more than the original amount of plasticizer
needed to formulate the DVA. The total amount of succinic anhydride
functionalized oligomer and plasticizer is also within the above
stated ranges of a minimum amount of about 2 phr, 5 phr, or 10 phr
to a maximum amount of 15 phr, 20 phr, 25 phr, 30 phr, or 35
phr.
In a preferred embodiment, the succinic anhydride functionalized
oligomer and plasticizer are present in the DVA in a ratio ranging
from 0.15 to 3.0. In another embodiment, the ratio is in the range
of 0.15 to 1.50. In another embodiment, the ratio of
polyisobutylene succinic anhydride to plasticizer is approximately
0.30 to 1.50.
In another preferred embodiment, the DVA is substantially free of
any acrylates. By substantially free, the DVA contains less than
0.5 phr of any acrylate or is preferably devoid of acrylate.
The invention, accordingly, provides the following embodiments: A.
A dynamically vulcanized alloy comprising at least one
isobutylene-containing elastomer; at least one thermoplastic resin,
and an anhydride functionalized oligomer, wherein the elastomer is
present as a dispersed phase of small highly vulcanized or
partially vulcanized particles in a continuous phase of the
thermoplastic resin; B. The alloy of embodiment A, wherein the
oligomer is selected from the group consisting of an alkyl, an
aryl, and an alkenyl oligomer. C. The alloy of embodiment A or B,
wherein the oligomer has a molecular weight in the range of 500 to
5000. D. The alloy of any preceding embodiment A to C, wherein the
anhydride functionality in the oligomer is either succinic
anhydride or maleic anhydride. E. The alloy of any preceding
embodiment A to D, wherein the anhydride functionalized oligomer is
a poly-n-alkyl succinic anhydride or a poly-iso-alkyl succinic
anhydride. F. The alloy of any preceding embodiment A to E, wherein
the functionalized oligomer is selected from the group consisting
of poly-isobutylene succinic anhydride, polyisobutene succinic
anhydride, polybutene succinic anhydride, polyisopentene succinic
anhydride, polypentene succinic anhydride, polyoctenyl succinic
anhydride, polyisooctenyl succinic anhydride, poly-hexenyl succinic
anhydride, and poly-dodecenyl succinic anhydride. G. The alloy of
any preceding embodiment A to F, wherein the alloy comprises 2 to
35 phr of the anhydride functionalized oligomer, based on the
amount of the isobutylene-containing elastomer in the alloy. H. The
alloy of any preceding embodiment A to G, wherein the alloy further
comprises a plasticizer, the plasticizer being selected from the
group consisting of polyamides, tertiary amines, secondary
diamines, esters, and sulfonamides. I. The alloy of any preceding
embodiment A to H, wherein the alloy is substantially free of any
acrylates. J. The alloy of any preceding embodiment A to I, wherein
said elastomer is a halogenated butyl rubber. K. The alloy of any
preceding embodiment A to J, wherein said elastomer is a copolymer
of isobutylene and an alkylstyrene. L. The alloy of any preceding
embodiment A to K, wherein said elastomer is a copolymer of
isobutylene and paramethylstyrene, and is optionally halogenated.
M. The alloy of any preceding embodiment A to L, wherein the
thermoplastic resin is selected from the group consisting of
polyamides, polyimides, polycarbonates, polyesters, polysulfones,
polylactones, polyacetals, acrylonitrile-butadiene-styrene resins,
polyphenyleneoxide, polyphenylene sulfide, polystyrene,
styrene-acrylonitrile resins, styrene maleic anhydride resins,
aromatic polyketones, ethylene vinyl acetates, ethylene vinyl
alcohols, and mixtures thereof. N. The alloy of any preceding
embodiment A to M, wherein the elastomer is present in the alloy in
an amount in the range of 2 to 90 weight percent.
EXAMPLES
Test methods are summarized in Table 1.
When possible, standard ASTM tests were used to determine the DVA
physical properties (see Table 1). Stress/strain properties
(tensile strength, elongation at break, modulus values, energy to
break) were measured at room temperature using an Instron.TM. 4204.
Tensile measurements were done at ambient temperature on specimens
(dog-bone shaped) width of 0.16 inches (0.41 cm) and a length of
0.75 inches (1.91 cm) length (between two tabs) were used. The
thickness of the specimens varied and was measured manually by A
Mahr Federal Inc. thickness guage. The specimens were pulled at a
crosshead speed of 20 inches/min. (51 cm/min.) and the
stress/strain data was recorded. The average stress/strain value of
at least three specimens is reported. Shore A hardness was measured
at room temperature by using a Zwick Durometer after 15 seconds
indentation. LCR viscosity was measured with a Dynisco.TM.
capillary rheometer at 30/1 L/D (length/diameter) at 220.degree. C.
at 1200 l/s. The melting point was measured by differential
scanning calorimetry at 10.degree./minute.
TABLE-US-00001 TABLE 1 Parameter Units Test Physical Properties,
press cured, 2 mm thickness sheets, 5 minutes @ 207.degree. C.
Hardness Shore A ASTM D2240 Modulus 10%, 50%, 100% MPa ASTM D412
Tensile Strength MPa ASTM D412 Elongation at Break % ASTM D412 LCR
Viscosity Pa s 30/1 L/D at 220.degree. C. at 1200 1/s Melting Point
.degree. C. Differential Scanning Calorimetry at 10.degree.
C./minute
Samples were prepared of both comparative DVAs, A and B of Table 3,
and exemplary DVAs made in accordance with the present invention.
The components used in the samples are identified in Table 2 below.
The PIBSA form for the practice of this invention is not restricted
to the examples used and other commercial offerings which are
diluted in oil may also be employed, especially if the molecular
weight of the starting PIBSA renders it too viscous. The PIBSAs may
also be heated so they can be easily dispensed in mixing equipment
and also to facilitate their incorporation and mixing.
TABLE-US-00002 TABLE 2 Commercial Component Brief Description
Source BIMSM Brominated para-methylstyrene- isobutylene copolymer,
0.75 mol % benzylic bromine, 2.5 mole % p- methylstyrene (prior to
bromination), MW = 450,000 g/mole, Mn = 184,000 g/mole, Mooney
viscosity, ML (1 + 8) 125.degree. C. = 45, Polyamide Nylon 6/66
random copolymer; MW.sub.n = UBE 5033B, copolymer 40,000 g/mole,
Ube 5033B random from UBE copolymer, 85 wt % nylon 6 and 15 wt
Chemical % nylon 6, 6 Compatibilizer Maleated ethylene ethyl
acrylate AR-2001, copolymer (mEEA) from Mitsui- DuPont Co., Ltd.
PIBSA 1 Polyisobutylene succinic anhydride, PIBSA 950 MW before
anhydride reaction = 950, (TPC950 .TM.), viscosity at 100.degree.
C. = 459 cSt, from Texas saponification # = 100 mg KOH/gm
Petrochemicals PIBSA 2 Polyisobutylene succinic anhydride,
Glissopal .TM. MW before anhydride reaction = 1,000, SA from
viscosity at 100.degree. C. = 480 cSt, BASF saponification # + 87
mg KOH/gm Plasticizer n-butylbenzene sulfonamide Uniplex .TM. 214,
Uniplex Chemical
Except for comparative sample A, the amount of elastomer,
polyamide, stabilizer blend, and curatives were identical for all
compositions. The stabilizer blend was present in the amount of
0.48 phr, and the curatives for each DVA consisted of 0.15 phr zinc
oxide, 0.30 phr zinc stearate, and 0.65 stearic acid for a total
additive amount of 1.58 phr. For comparative sample A, only the
amount of elastomer was greater, to obtain the same phr as
comparative sample B. For each example identified below, the DVA
was prepared in the same manner, using a 85 cm.sup.3 Brabender.TM.
mixer. Both comparative and exemplary DVA samples were tested to
determine the physical characteristics. The compositions and test
results are set forth below in Table 3.
When the full amount of compatibilizer, the mEEA, is replaced with
the polyisobutylene succinic anhydride and the amount of
plasticizer is not modified, the strength characteristics of the
DVA, the shore A hardness and ultimate tensile strength, are
improved. The elastic nature of the DVA is also improved, showing
an increase in the 10% modulus and maximum strain. The viscosity
values of the material, as measured by the LCR values, is not
significantly impacted at 5 phr PIBSA whereas at 10 phr PIBSA the
viscosity is significantly reduced. For these DVAs, lower viscosity
means more fluidity which is a positive characteristic since
shaping operations to make film or parts are improved due to the
improved flow of the material.
TABLE-US-00003 TABLE 3 A B 1 2 3 4 5 BIMSM 110.05 100.0 100.0 100.0
100.0 100.0 100.0 Talc 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Polyamide
copolymer 62.96 62.96 62.96 62.96 62.96 62.96 62.96 Compatibilizer
-- 10.05 -- -- -- -- -- PIBSA 1 -- -- 10.05 5.03 5.03 5.03 5.03
Plasticizer 26.99 26.99 26.69 26.69 13.49 6.74 3.37 Additives 1.58
1.58 1.58 1.58 1.58 1.58 1.58 Total PHR 203.58 203.58 203.58 198.26
185.06 178.31 174.94 phr of PIBSA and 36.74 32.02 18.52 11.77 8.4
plasticizer Ratio of PIBSA to 0.38 0.188 0.373 0.746 1.49
plasticizer Test Results Shore A Hardness, 80 77 82 85 79 78 72 at
15 s ultimate tensile strength, 7.29 6.76 8.17 10.5 6.95 6.08 5.58
MPa 10% modulus, MPa 2.95 2.37 3.53 4.14 3.13 2.73 2.18 Maximum
Strain, % 89 98 128 114 80 93 142 LCR Viscosity (Pa-s) @ 391 334
235 326 316 298 281 1200 (1/s) @220.degree. C., (L/D 30/1) Melting
Point, .degree. C. -- 182 188 184 192 193 194
With obtaining improved properties to desirable characteristics of
the DVA, the inventors explored the reduction in the plasticizer.
As seen in example 3, reduction of the plasticizer by one-half
fractionally reduces the hardness properties of the DVA, improves
the 10% modulus values, and only negatively impacts the maximum
strain of the DVA. Data from further reduction of the plasticizer
shows that an almost complete removal of the plasticizer negatively
impacts the elastic nature of the DVA. The melt viscosity of the
inventive samples is reduced relative to the comparative samples,
which is an improved and sought after trait for processability and
fabricability, or drapeability, of the product during shaping
operations such as extrusion or film blowing.
A second PIBSA, having a 1,000 molecular weight olefin prior to the
anhydride reaction, was also tested, with the composition and
results shown in Table 4.
TABLE-US-00004 TABLE 4 6 7 8 9 10 11 12 13 BIMSM 100.0 100.0 100.0
100.0 100.0 100.0 100.0 100.0 Talc 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0
Polyamide 62.96 62.96 62.96 62.96 62.96 62.96 62.96 62.96 copolymer
Compatibilizer -- -- -- -- -- -- -- -- PIBSA 2 5.03 5.03 5.03 5.03
10.05 10.05 10.05 10.05 Plasticizer 26.69 13.49 6.74 3.37 26.69
13.49 6.75 3.37 Additives 1.58 1.58 1.58 1.58 1.58 1.58 1.58 1.58
Total PHR 198.26 185.06 178.31 174.94 203.58 190.08 183.34 179.96
phr of PIBSA and 32.02 18.52 11.77 8.4 36.74 23.54 16.8 13.42
plasticizer Ratio of PIBSA to 0.188 0.373 0.746 1.49 0.376 0.745
1.48 2.98 plasticizer Test Results Shore A Hardness, 83 78 76 76 81
78 78 75 at 15 s ultimate tensile 7.89 7.12 6.22 5.38 8.81 6.54
5.49 5.36 strength, MPa 10% modulus, 3.5 3.37 2.96 2.52 3.31 2.94
3.08 2.43 MPa Maximum Strain, % 100 84 86 95 144 137 71 96 LCR
Viscosity (Pa-s) 330 303 310 288 264 269 265 266 @ 1200 (1/s)
@220.degree. C., (L/D 30/1) Melting Point, .degree. C. 184 189 189
193 190 190 195 196
In comparison to comparative DVA B, the DVA of example 6 shows
improved solid state strength properties of shore A and ultimate
tensile strength and improved elastic properties with a small
decrease in viscosity. The decrease in viscosity is beneficial
since this indicated improved fluidity of the material in the
melt.
Similar to PIBSA1, the use of PIBSA2 also enabled a significant
reduction in the amount of plasticizer without a comprising in the
material properties.
To analyze the limits of reduction in the plasticizer and inclusion
of the oligomeric polyisobutylene succinic anhydride, further
examples 10 to 13 were prepared. Exemplary DVAs with comparable
ratios of PIBSA to plasticizer were compared. The Shore A hardness
and ultimate tensile strength properties are similar, with
decreases in LCR viscosities for the higher amount of PIBSA; again,
a desired characteristic in the DVA.
With a further decrease in the plasticizer, significantly
increasing the ratio of PIBSA to plasticizer, the 10% modulus is
further decreased, suggesting a limit for the reduction of
plasticizer is being approached.
In the DVA, by substituting the succinic anhydride polymer in the
alloy, the solid state strength properties are maintained while
improved is the desired fluidity of the DVA as measured by the
various reductions in LCR viscosity. Also desired is a Shore A
hardness of at least 70, and most preferably at least 75.
The inventive compositions can be used to make any number of
articles. In one embodiment, the article is selected from tire
curing bladders, tire innerliners, tire innertubes, and air
sleeves. In another embodiment, the article is a hose or a hose
component in multilayer hoses, such as those that contain polyamide
and especially polyamide 12 as one of the component layers. Other
useful goods that can be made using compositions of the invention
include air spring bladders, seals, molded goods, cable housing,
and other articles disclosed in THE VANDERBILT RUBBER HANDBOOK, P
637-772 (Ohm, ed., R. T. Vanderbilt Company, Inc. 1990).
* * * * *